1. Field of the Invention
The present invention relates to a high-quality bearing steel having excellent durability life and cold workability and used for ball bearings, roller bearings and the like, and a manufacturing method therefor.
2. Description of the Prior Art
Bearing steel must satisfy various properties including those relating to durability life, impact fatigue, cold workability and the like. In particular, durability life is becoming increasingly important with trends toward heavier loads and higher speed together with the requirements of higher performance in industrial machinery and vehicles. Studies are being made to develop a steel having higher durability life.
In order to improve durability life, a conventional method was proposed wherein the O content of the steel is decreased to reduce oxide inclusions such as Al.sub.2 O.sub.3. In some applications, another conventional method was proposed which uses a special smelting method such as VAR or ESR so as to control the solid texture and to reduce the amount of non-metallic inclusions.
However, in the conventional method of simply reducing the O content of the steel, a satisfactory long durability life cannot be obtained in some applications. Again, the latter method is costly and not suitable to mass-production.